Sinn Féin leader Mary Lou McDonald has told the Dáil that the complaint against former party TD Brian Stanley was very serious and left the complainant traumatised and distressed.
Amid a welter of controversies engulfing Sinn Féin, Ms McDonald set out the party's position in a lengthy statement to the Dáil.
He is the second party TD to leave Sinn Féin in a week following the resignation of Kildare South TD Patricia Ryan.
And today it also emerged that former party Senator Niall Ó Donnghaile had sent an inappropriate text message to a 17 year-old boy.
Stanley complaint 'very serious' - McDonald tells Dáil
Ms McDonald told the Dáil today that she was unaware of the detail of the complaint against Mr Stanley until Saturday night when he issued a statement.
"The complaint made against Deputy Stanley is very serious. The complaint relates to an incident that took place in October 2023 and relates to Deputy Stanley’s personal behaviour leaving the complainant, in her words, traumatised and distressed," she said
Mr Stanley denies any misbehaviour.
Ms McDonald said Mr Stanley raised a "very serious" counter allegation against the complainant also relating to "the incident of October 2023".
The Dublin Central TD said Mr Stanley was advised to go to the gardai but had not done so.
On Sunday, Sinn Féin referred both complaints to An Garda Síochána at Kevin Street Garda Station.
She defended her party’s actions and internal disciplinary process saying they was conducted in a correct and fair manner.

Ó Donnghaile controversy
Ms McDonald also addressed the separate controversy relating to former senator Niall Ó Donnghaile.
She said that a complaint was received by a party councillor on September 11 2023 that an inappropriate text message was sent by the senator to a 17 year-old male party member.
A formal party procedure was initiated and it emerged that a second individual, an adult, also said they had received inappropriate text messages from the former Senator.
On 13 September, Mr Ó Donnghaile was suspended from the party and Sinn Féin passed on the details to the PSNI and social services.
No formal investigation followed and the PSNI told Sinn Féin that the young person was content with the actions taken by the party.
"There was no finding of illegality and no criminal charges were pursued."
On 5 October, the party met Mr Ó Donnghaile and he confirmed he would resign from the Seanad and Sinn Féin.
Other parties have questioned why Ms McDonald praised Mr Ó Donnghaile when his resignation was formally announced in December 2023 and why it took two months for that announcement.
She said the party had received legal advice against naming him as there was no criminal charge brought against him.

McDonald hits out at 'political football'
Ms McDonald said it was a legitimate question to ask why Sinn Fein did not inform the Oireachtas.
She said in summer 2021, he was on extended leave from his duties in the Seanad, due to very serious mental health issues.
Following the complaint, she said they were advised Mr Ó Donnghaile was again suffering from a mental health crisis and was deemed medically unfit to work by his doctor.
Ms McDonald said: "That is not to make an excuse for his behaviour but we had very serious concerns for his mental heath and his safety and I still have some of those concerns."
But the Sinn Féin leader also took aim at others attempting to make a "political football" out of the controversies.
"We will call out political opponents attempting to exploit these issues for electoral advantage. And ladies and gentleman, your cynicism is matched only by your hypocrisy which is truly, truly breathtaking," she said.
Other speakers were not impressed with the Sinn Féin leader’s defence of her party’s actions.
Labour Party leader Ivana Bacik said Ms McDonald's comments were "frankly incredible" and she asked whether there was a parallel justice system being run by a political party".
Social Democrats leader Holly Cairns said Ms McDonald had failed to explain why she issued a glowing statement when Mr Ó Donnghaile left the Seanad.
Minister of State at the Department of Health Anne Rabbitte said that every party has rotten apples and the true measure of it "is not about whether they have these rotten apples, it's how they deal with them."
Sinn Féin's management of recent controversies "has been highly flawed" she said.
She accused the party of "flip-flopping on criminality" and engaging in "dismiss or deflect".
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